docs: def _generate_security_groups(config_key):
      """Read config file and generate security group dict by environment.
  
      Args:
          config_key (str): Configuration file key
  
      Returns:
          dict: of environments in {'env1': ['group1', 'group2']} format
      """
      raw_default_groups = validate_key_values(CONFIG, 'base', config_key, default='')
      default_groups = _convert_string_to_native(raw_default_groups)
      LOG.debug('Default security group for %s is %s', config_key, default_groups)
  
      entries = {}
      for env in ENVS:
          entries[env] = []
  
      if isinstance(default_groups, (list)):
          groups = _remove_empty_entries(default_groups)
          for env in entries:
              entries[env] = groups
      elif isinstance(default_groups, (dict)):
          entries.update(default_groups)
  
      LOG.debug('Generated security group: %s', entries)
      return entries